Methods, apparatuses and system for transmission of a connection request message in a wireless communications system

ABSTRACT

A terminal device for use in a wireless telecommunications system includes: a transceiver configured to perform wireless communication with a base station; and a controller configured to: control the transceiver to detect a wireless paging signal from the base station; detect whether the paging signal includes information defining an allocation of a communications resource for use by the terminal device to send a connection request message to the base station; control the transceiver, in response to a detection that the paging signal does not include information defining the allocation of the communications resource, to perform a radio channel allocation procedure with the base station for the terminal device to be allocated the communications resource; and control the transceiver to establish wireless communication with the base station by sending the connection request message using the allocated communications resource.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT filing PCT/EP2016/069824 filedAug. 22, 2016, and claims priority to European Patent Application 15186988.0, filed in the European Patent Office on Sep. 25, 2015, theentire contents of each of which being incorporated herein by reference.

BACKGROUND Field

This disclosure relates to wireless telecommunications.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, is neitherexpressly or impliedly admitted as prior art against the presentdisclosure.

Low Complexity MTC (Machine Type Communication) UE (user equipment)(LC-MTC) has been proposed, for example in the 3GPP (3^(rd) GenerationPartnership Project). Features of LC-MTC UE include low complexity,potential for low cost, coverage enhancement and potential for reducedpower consumption.

A technique to reduce complexity and cost for LC-MTC UE is to restrictthe UE to operate within 6 PRBs (Physical Resource Blocks). The systembandwidth is therefore divided into multiple 6 PRB narrowbands and theLC-MTC UE is expected to be able to tune into any of these narrowbands.

In the coverage enhancement (CE) feature, the coverage for LC-MTC isextended by 15 dB (decibels) relative to that of a so-called Cat-1 UE.The main technique for CE is via numerous repetitions of the samemessage, with the received versions being combined in order to improvethe signal to noise ratio of the combination as compared to that of anyindividual instance of the message. Numerous repetition of the samemessage would significantly decrease the spectral efficiency. Therefore,for operation in CE mode, multiple coverage enhancement levels (CElevels) or repetition levels are introduced such that the appropriatenumber of repetitions is used at each CE level.

In previously proposed arrangements, for a network initiated call, thenetwork pages a UE in idle mode to initiate the UE to start a RadioResource Control (RRC) connection. The UE would then start a RACH(Random Access Channel) process, which consists of transmitting aPhysical Random Access Channel (PRACH) preamble and receiving a RAR(Random Access Response) from the eNB (e-NodeB). Since more than one UEmay access the network using PRACH within the same time, the RAR wouldindicate which PRACH preamble the network responds to. The RAR alsoprovides an uplink grant that schedules the subsequent Message 3 wherethe UE would send a RRC Connection Request message.

For operation in CE mode, the PRACH (preamble) needs to be repeatednumerous times. It has been agreed in 3GPP that there will be 3 CElevels for PRACH, each CE level representing a greater number ofrepetitions (and so, at least in principle, the ability to cope with agreater range and thus a worse signal to noise ratio). The LC-MTC UEwould perform several PRACH attempts in each CE level and if it failsafter the maximum number of attempts is reached, it will move to thenext CE level and start a further set of PRACH attempts. Similarly, theRAR would also be sent in a repetitive manner. A RAR time window mayalso be used in order to spread the load of the RAR and the LC-MTC UEwould need to decode each MAC PDU within the time window.

In general, these processes could consume a lot of LC-MTC UE batterypower and also use up radio resources over a potentially extendedperiod.

It is a constant aim to improve the operation and efficiency of wirelessnetwork systems.

SUMMARY

The present disclosure can address or mitigates the problems discussedabove.

Respective aspects and features of the present disclosure are defined inthe appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 schematically illustrates a mobile telecommunications system;

FIG. 2 provides a simplified schematic diagram of the structure of adownlink of a wireless access interface;

FIG. 3 provides a simplified schematic diagram of the structure of anuplink of a wireless access interface;

FIG. 4 schematically illustrates a base station;

FIG. 5 schematically illustrates a user equipment (UE);

FIG. 6 schematically illustrates an RACH (random access channel)process;

FIG. 7 is a schematic flowchart of a paging operation;

FIG. 8 is a schematic timing diagram illustrating a part of a pagingoperation;

FIG. 9 is a schematic timing diagram of a communication interaction;

FIG. 10 is a schematic flowchart illustrating a part of a communicationinteraction;

FIGS. 11 and 12 are schematic timing diagrams relating to acommunication interaction using coverage enhancement (CE);

FIG. 13 is a schematic flowchart summarizing a method of operation of aUE; and

FIG. 14 is a schematic diagram summarizing a method of operation of abase station.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 provides a schematic diagram of a mobile telecommunicationssystem 100, where the system includes mobile communications terminals(such as UEs) 101, infrastructure equipment 102 and a core network 103.

The infrastructure equipment may also be referred to as a base station,network element, enhanced Node B (eNodeB or eNB) or a coordinatingentity for example, and provides a wireless access interface to the oneor more communications terminals within a coverage area or cell. The oneor more mobile communications terminals may communicate data via thetransmission and reception of signals representing data using thewireless access interface. The infrastructure equipment 102 iscommunicatively linked to core network components such as a servinggateway support node (SGSN) 103A, a packet gateway node 103B and anexternal network 103C, which may be connected to one or more othercommunications systems or networks which have a similar structure tothat formed from communications terminals 101 and infrastructureequipment 102.

The core network 103 may also provide functionality includingauthentication, mobility management, charging and so on for thecommunications terminals served by the network entity. The mobilecommunications terminals 101 of FIG. 1 may also be referred to ascommunications terminals, user equipment (UE), terminal devices and soforth, and are configured to communicate with one or more othercommunications terminals served by the same or a different coverage areavia the infrastructure equipment. These communications may be performedby transmitting and receiving signals representing data using thewireless access interface over the two way communications linksrepresented by lines 104 to 109, where 104, 106 and 108 representdownlink communications from the infrastructure equipment to thecommunications terminals and 105, 107 and 109 represent uplinkcommunications from the communications terminals to the infrastructureequipment. The telecommunications system 100 may operate in accordancewith a telecommunications protocol. For instance in some examples thesystem 100 may generally operate in accordance with a 3GPP Long TermEvolution (LTE) standard where the network entity and communicationsterminals are commonly referred to as eNodeB and UEs, respectively.

A brief description of the LTE wireless access interface is explained inthe following paragraphs with reference to FIGS. 2 and 3 to support theexplanation of the example embodiments of the present technique whichare provided in the following paragraphs.

Mobile telecommunications systems such as those arranged in accordancewith the 3GPP defined Long Term Evolution (LTE) architecture use anorthogonal frequency division modulation (OFDM) based wireless accessinterface for the radio downlink (so-called OFDMA) and a single carrierfrequency division multiple access scheme (SC-FDMA) on the radio uplink.The down-link and the up-link of a wireless access interface accordingto an LTE standard is presented in FIGS. 2 and 3.

FIG. 2 provides a simplified schematic diagram of the structure of adownlink of a wireless access interface that may be provided by or inassociation with the base station of FIG. 1 when the communicationssystem is operating in accordance with the LTE standard. In LTE systemsthe wireless access interface of the downlink from a base station to aUE is based upon an orthogonal frequency division multiplexing (OFDM)access radio interface. In an OFDM interface the resources of theavailable bandwidth are divided in frequency into a plurality oforthogonal subcarriers and data is transmitted in parallel on aplurality of orthogonal subcarriers, where bandwidths between 1.4 MHZand 20 MHz bandwidth may be divided into orthogonal subcarriers. Not allof these subcarriers are used to transmit data (some are used forfeatures such as the cyclic prefix of the OFDM symbols). The number ofsubcarriers varies between 72 subcarriers (1.4 MHz) and 1200 subcarriers(20 MHz). In some examples the subcarriers are grouped on a basis of2^(n), for example 128 to 2048, so that both a transmitter and areceiver can use an inverse and a forward Fast Fourier Transform toconvert the sub-carriers from the frequency domain to the time domainand from the time domain to the frequency domain respectively. Eachsubcarrier bandwidth may take any value but in LTE it is fixed at 15kHz. As shown in FIG. 2, the resources of the wireless access interfaceare also temporally divided into frames where a frame 200 lasts 10 msand is subdivided into 10 subframes 201 each with a duration of 1 ms.Each subframe 201 is formed from 14 OFDM symbols and is divided into twoslots 220, 222 each of which comprise six or seven OFDM symbolsdepending on whether a normal or extended cyclic prefix is beingutilised between OFDM symbols for the reduction of inter symbolinterference. The resources within a slot may be divided into resourcesblocks 203 each comprising 12 subcarriers for the duration of one slotand the resources blocks further divided into resource elements 204which span one subcarrier for one OFDM symbol, where each rectangle 204represents a resource element. However of particular relevance inunderstanding the example embodiments of the present technique are thedownlink control channel referred to as the physical downlink controlchannel (PDCCH) and a shared channel of resources for transmitting datato UEs which is the physical downlink shared channel (PDSCH).

FIG. 3 provides a simplified schematic diagram of the structure of anuplink of an LTE wireless access interface that may be provided by or inassociation with the base station of FIG. 1. In LTE networks the uplinkwireless access interface is based upon a single carrier frequencydivision multiplexing FDM (SC-FDM) interface and downlink and uplinkwireless access interfaces may be provided by frequency divisionduplexing (FDD) or time division duplexing (TDD), where in TDDimplementations subframes switch between uplink and downlink subframesin accordance with predefined patterns. However, regardless of the formof duplexing used, a common uplink frame structure is utilised. Thesimplified structure of FIG. 3 illustrates such an uplink frame in anFDD implementation. A frame 300 is divided in to 10 subframes 301 of 1ms duration where each subframe 301 comprises two slots 302 of 0.5 msduration. Each slot is then formed from seven OFDM symbols 303 where acyclic prefix 304 is inserted between each symbol in a manner equivalentto that in downlink subframes.

The LTE data or datagram is transmitted on the PDSCH on the downlink andon the PUSCH in the uplink. The resources on the PDSCH and the PUSCH areallocated to the terminal device by the base station.

FIG. 4 schematically illustrates a base station 102 in more detail. Thebase station 102 includes a transmitter (Tx) 400 for transmittingsignals via a wireless access interface (and via an antenna 430) to theone or more communications devices or UEs, and a receiver (Rx) 410 toreceive signals from the one or more UEs within the coverage area of thebase station. A controller 420 controls the transmitter 400 and thereceiver 410 to transmit and receive the signals via the wireless accessinterface. The transmitter 400 and receiver 410 together form atransceiver. The controller 420 may perform a function of controllingthe allocation of communications resource elements of the wirelessaccess interface and may in some examples include a scheduler forscheduling transmissions via the wireless access interface for both anuplink and the downlink. Operations of a base station discussed inconnection with the description below may be undertaken or overseen, atleast in part, by the controller 420. FIG. 4 therefore provides anexample of a base station for use in a wireless telecommunicationssystem, the base station comprising a transceiver 400, 410 configured toperform wireless communication with a terminal device; and a controller420 configured to control the transceiver to send a wireless pagingsignal to the terminal device.

FIG. 5 schematically illustrates a UE 101 in more detail. The UE 101includes a transmitter 500 associated with an antenna 530 fortransmitting signals on the uplink of the wireless access interface tothe base station 102 and a receiver 510 for receiving signalstransmitted by the base station 102 on the downlink via the wirelessaccess interface. The transmitter 500 and the receiver 510 arecontrolled by a controller 520. The transmitter 500 and receiver 510together form a transceiver. Operations of a UE discussed in connectionwith the description below may be undertaken or overseen, at least inpart, by the controller 520. In example embodiments of the presentdisclosure, the UE 101 is a so-called Low Complexity Machine TypeCommunication (LC-MTC) terminal device. FIG. 5 therefore provides anexample of a terminal device for use in a wireless telecommunicationssystem, the terminal device comprising: a transceiver 500, 510configured to perform wireless communication with a base station; and acontroller 520 configured to control the transceiver to detect awireless paging signal from the base station.

FIG. 6 schematically illustrates a previously proposed RACH (randomaccess channel) process.

For a network initiated call, the network pages a terminal device inidle mode to initiate the terminal device to start a Radio ResourceControl (RRC) connection. The terminal device starts a RACH (RandomAccess Channel) process, which consists of transmitting a PhysicalRandom Access Channel (PRACH) preamble 600 and receiving a RAR (RandomAccess Response) 610 from the base station. Since more than one terminaldevice may access the network using PRACH within the same time, the RARcan indicate which PRACH preamble the network responds to. The RAR alsoprovides an uplink grant that schedules the subsequent Message 3 (620)by which the terminal device sends a RRC Connection Request message.

Multiple RARs can be multiplexed into a MAC PDU (Medium Access ControlProtocol Data Unit) and this MAC PDU is transmitted within a RAR timewindow, 3 subframes after the transmission of the PRACH preamble. TheRAR time window size can be 2 to 10 subframes, which is to say that upto 10 MAC PDUs (containing RARs) can be sent within the RAR time window.

The terminal device decodes each MAC PDU within the RAR time windowuntil it finds its RAR. This is followed by the base stationtransmitting a Message 4 (RRC Connection Setup) 630 and the terminaldevice transmitting a Message 5 (RRC Connection Setup Complete) 640 tocomplete the RRC connection.

The information which the base station provides to the terminal devicein the RAR (Random Access Response) message 610 may include one or moreof the following:

(a) allocation of a temporary identifier or RNTI (Radio NetworkTemporary Identifier). An initially temporary identifier is allocated tothe base station which is made permanent after a successful RACHprocedure. The permanent identifier is referred to as the cell RNTI orC-RNTI.

(b) timing advance information. This takes into account a transmissiondelay between the base station and the terminal device so as to be usedto adjust the expected timings of communications to take into accountthe transmission delay.

(c) allocation of uplink resources. The base station provides sufficientresource and/or scheduling information in the RAR response for theterminal device to be able to send message 3.

In other words, a communications resource provided by the base stationcomprises one or more of: one or more radio frequency band; a temporaryradio network identifier, a timing advance parameter and one or moretransmission time slots. Note that more than one radio frequency bandcan be defined as the communications resource if a frequency hopping orsimilar arrangement is in use. Note that plural time slots can bedefined as the communications resource if repetition is used (which isto say, the plural time slots relating the repeated transmissions can bedefined by a single allocation of uplink resources.

The present disclosure recognizes that for operation in coverageenhanced (CE) mode, which makes use of message repetition to providemore robust communications in poor signal strength or noisyenvironments, the PRACH (preamble) needs to be repeated numerous times.The number of repetitions depends upon the so-called CE level or mode. Aterminal device according to LC-MTC potentially performs several PRACHattempts in each CE level and if it fails after the maximum number ofattempts is reached, it will move to the next higher CE level(representing a next higher number of repetitions) and restart a furtherset of PRACH attempts. Similarly, the RAR response is also sent in arepetitive manner. The present disclosure notes that both of thesefactors could lead to the consumption of significant amounts of batterypower in an example LC-MTC terminal device, and could also tie up radioresources over an extended period.

Embodiments of the present disclosure relate to techniques to alleviatethese problems, based around providing additional information as part ofa paging operation.

FIG. 7 is a schematic flow chart of a paging operation, which includesthe start of a paging cycle at a step 700.

Paging is used for network-initiated communication with a terminaldevice and involves, at the start of a paging cycle, the terminal devicewaking up in order to detect paging information being transmitted. Thepaging cycles occur from time to time (for example, periodically) so aterminal device can remain in a quiescent or idle state except when thepaging cycle is taking place.

At a step 720, the terminal device detects whether any paging messagesare directed to that terminal device. It may well be that in anyparticular paging cycle, there might be no messages directed to thatterminal device. However, in the schematic example of FIG. 7, the basestation is in fact paging that particular terminal device at a step 730.

In response to detection of a paging message directed to that terminaldevice, the terminal device initiates wireless communication with thebase station at a step 740, as an example of the controller of theterminal device controlling the transceiver to establish wirelesscommunication with the base station by sending the connection requestmessage using the allocated communications resource.

In contrast to previous proposed RRC processes, however, in the presentembodiments some information is provided as part of or in associationwith the paging transmission to allow message 3 (FIG. 6) to be sentdirectly at the step 740, or in other words avoiding the need for thePRACH (preamble) and the RAR response.

Therefore, instead of requiring the terminal device to transmit a PRACHand to wait for an RAR (each of which may occur at multiple repetitionsas discussed above) the paging process itself can provide the necessaryinformation for the terminal device to send the RRC connection requestat message 3. This can therefore reduce the need for, or remove, thefirst two steps of the RACH process shown in FIG. 6. In turn, thisprovides potential improvements in power consumption and/or networkusage.

In particular, as noted above, the two steps removed or reduced withrespect to the RACH process of FIG. 6 require multiple PRACHrepetitions, ramping up to higher numbers of repetitions if successfultransmission is not achieved, blind decoding for MPDCCH messages thatschedule the RAR and also a blind decoding for an RAR within an RARwindow. These can consume significant amounts of battery power comparedto the remaining steps (message 3 onwards) where RRC connection messagesare exchanged. Furthermore, the present technique can also reduce oreliminate contention at the preamble stage since the LC-MTC terminaldevice is provided with an uplink grant and therefore information suchas the so-called Backoff Indicator that is in the MAC PDU (carrying theRAR) are not required. Since the base station knows specifically whichLC-MTC terminal device it is providing the uplink grant for, informationsuch as that indicating which preamble the base station is responding tois also not required.

At a general level, the information required for the LC-MTC terminaldevice to transmit message 3 (RRC connection request) contains at leastthe uplink grant and temporary RNTI.

FIG. 8 is a schematic timing diagram illustrating a part of a pagingoperation in which message 3 grant information (the information definedabove, or in other words, a communications resource provided by the basestation comprising one or more of: a radio frequency band, a temporaryradio network identifier and a transmission time slot) which is requiredfor the terminal device to go straight to issuing message 3 without theneed for the PRACH (preamble) and RAR response is contained in the DCI(MPDCCH) 800 which schedules the paging message 810, and/or in thepaging message 810 itself (carried by the PDSCH). This is an example ofthe paging signal comprising a data field defining the communicationsresource. Where the message 3 grant information is in the paging message810, this is an example of the paging signal comprising a first portion800 and a second portion 810, the first portion comprising schedulingdata scheduling the transmission of the second portion, the secondportion comprising a data field defining the communications resource.Where the message 3 grant information is in the DCI 800, this is anexample of the paging signal comprising a first portion 800 and a secondportion 810, the first portion comprising scheduling data scheduling thetransmission of the second portion, the first portion comprising a datafield defining the communications resource.

A so-called paging occasion is defined, for example, on a periodicbasis, as a time t₀ where the terminal device wakes up from a quiescent“DRX” (discontinuous reception) mode and monitors the MPDCCH searchspace for a possible DCI (downlink control information) which schedulesthe paging message. At the end of the MPDCCH search space (takingrepetition into account) the terminal device detects an MPDCCH 800 anddecodes it. The decoded MPDCCH 800 provides scheduling information toallow the terminal device to detect and decode the PDSCH containing thepaging message at time t₂.

In some examples, the paging messaging 810 contains not only theidentifier for the particular terminal device such as an IMSI(international mobile subscriber identity) but also the message 3 grantinformation (an uplink grant and a temporary RNTI) to allow message 3 tobe sent without the need for the PRACH (preamble) and RAR response.Using this information, the terminal device sends message 3 820 usingthe PUSCH resource provided in the message 3 grant.

In another example, instead of including the message 3 grant informationin the paging message 810, it is instead (or even, in some examples, aswell) included in the DCI 800 that schedules the paging message. Thisarrangement can be useful when the number of terminal devices to bepaged at a current paging cycle is small or even one.

In other examples, the DCI 800 can contain part of the message 3 grantinformation that is common to all currently paged terminal devices, andthe paging message 810 contains the remaining (terminal device-specific)information. For example, the DCI 800 may contain a reference (base)narrowband where the PUSCH for message 3 is to be transmitted, and thepaging message 810 contains an offset to this reference narrowband topinpoint an exact narrowband PRB (physical resource block) fortransmission of the PUSCH message 3. These embodiments can provide aslight reduction in the quantity of data needed to transmit the message3 grant information.

Features relating to timing advance will now be discussed.

First, comparison will be made with timing issues relating to thepreviously proposed RACH process described with reference to FIG. 6. Inthe previously proposed process, the first uplink transmission such asthe PRACH preamble would typically arrive later within the designateduplink subframe at the base station because of a propagation delay. FIG.9 is a schematic timing diagram to illustrate this point. Here, the basestation transmits a paging message at a time t₀ in a subframe n to theterminal device. Because of propagation delays the terminal devicereceives the paging message a short time (ΔT ms) later at a time t₁.Assuming the terminal device transmits the uplink transmission, PRACH,at subframe n+4 at t₃, the same propagation delay ΔT means that it wouldarrive at the base station at a time t₄. However, the correspondingsubframe n+4 at the base station started at a time t₂. This would meanthat the PRACH arrives late, by a total delay TA. In the previouslyproposed arrangement of FIG. 6 this is corrected by the timing advanceresponse, that is to say that the base station requests the terminaldevice to advance its transmissions (send them earlier) by TA ms.

In the present examples, message 3 is the first uplink transmission bythe terminal device, instead of the PRACH preamble. Message 3 istherefore not timing advanced to arrive at the subframe boundary,because timing advance information has not yet been provided by the basestation (in turn, because the RAR response has been omitted).

Example embodiments allow the base station to cope with this delay, andFIG. 10 is a schematic flowchart relating to such a process.

A step 1000 of FIG. 10 relates to the sending of the downlink paginginformation, as an example of a base station controller being configuredto control the transceiver to send a wireless paging signal to theterminal device, the paging signal comprising information defining anallocation of a communications resource for use by the terminal deviceto send a connection request message to the base station; and to controlthe transceiver to establish wireless communication with the terminaldevice by receiving the connection request message using the allocatedcommunications resource. At a step 1010, an uplink message (message 3)is detected during the sub frame n+4 (relative to the subframe n atwhich the paging message was sent). A step 1020 relates to the basestation continuing to detect the uplink message during one or morefurther subframes following the subframe n+4.

In the example of FIG. 9, this would mean that the base station reservesnot only the subframe n+4 but also the subframe n+5 to receive themessage 3, in order to account for potentially delayed propagation fromthe terminal device.

More generally, the number of subframes to be reserved in this way candepend upon the repetition level. If the number of repetitions formessage 3 (according to the CE mode in use) is R, then the base stationwould reserve the subframe n+4 and R additional uplink subframes for themessage 3 transmission. This provides an example of the base stationbeing configured to selectively operate at multiple coverage enhancement(CE) modes for communication with the terminal device, each CE modecorresponding to a different respective number of repetitions ofwireless data signals to or from the terminal device; and the controllerof the base station being configured to control the transceiver toreceive the connection request message in the defined subframe and anumber of temporally following subframes dependent upon the number ofrepetitions used in the CE mode applicable to communications from theterminal device. In examples, the number of temporally followingsubframes is equal to the number of repetitions.

In the arrangement of FIG. 6, the timing advance information to alignuplink messages with subframe boundaries was sent in the MAC PDUcontaining the RAR response and also transmitted during connection fromthe MAC layer. For operation under the present examples, the timingadvance information can instead be transmitted to the terminal device byone or more of the following:

-   (a) In the HARQ (Hybrid automatic repeat request)    acknowledgment/negative acknowledgement DCI during a retransmission    of message 3:-   (b) In message 4: and/or-   (c) By transmission of a timing advance control MAC message to the    terminal device after message 5. This would require the base station    to reserve an additional subframe to absorb the last PUSCH    repetition carrying message 5.

In terms of detection of the required timing advance, in the previouslyproposed examples the base station could use the PRACH preamble todetect the delay timing due to the propagation delay, by using acorrelator function on the preamble. In the present examples, the PRACHpreamble is not sent, but in example embodiments a preamble can betransmitted by the terminal device, for example prior to transmission ofmessage 3. That preamble, and/or the requirement for that preamble,and/or the RACH resource to be used for that preamble, can be indicatedby the base station in the DCI which schedules the paging message or thepaging message itself. This preamble can be different from those usedfor PRACH preamble.

Features concerning potential changes in CE level will now be discussed.As discussed, CE levels relate to the terminal device being configuredto selectively operate at multiple coverage enhancement (CE) modes, eachCE mode corresponding to a different respective number of repetitions ofwireless data signals to or from the terminal device.

In example embodiments, an LC-MTC terminal device in idle or quiescentmode does not inform the network if there is a change in CE level.Therefore, a base station is not necessarily aware of the terminaldevice's current CE level. In examples, a consequence of this is thatmessage 3 is transmitted at the highest CE level (that is to say, the CElevel or mode corresponding to a highest number of repetitions).

It has been proposed that the paging message be targeted at a differentCE level or mode, where an arrangement is used in which the DCI whichschedules the paging message (that is to say, the MPDCCH search space)and the paging message itself can occupy different communicationresources (for example, a different narrowband and/or a different timeperiod). Therefore, in example embodiments, where a paging messageoccupies a different CE level (different to the maximum CE level ordifferent to the CE level currently in use by the terminal device), thepaging message will provide message 3 grant using resources thatcorrespond to that CE level.

In FIG. 11, a paging cycle starts at a time t₀, and three differentDCIs, corresponding to three different MPDCCH search spaces, areprovided to schedule three respective paging messages. In particular,the three different DCIs 1100, 1110, 1120 relate to respective CE levels1, 2, 3, where CE level 3 represents a higher number of repetitions thanCE level 2, which in turn represents a higher number of repetitions thanCE level 1. Each of these DCIs schedules a respective paging message1130, 1140, 1150, again at CE levels 1, 2 and 3 respectively. Thisprovides an example of the base station controller being configured tocontrol the transceiver to send multiple paging signals at differentrespective CE modes, each paging signal defining a respectivecommunications resource for use by the terminal device.

Depending on current propagation conditions, signal strength, noiseconditions and so on, the terminal device may be able to detect thepaging message at CE level 1, in which case the terminal device uses CElevel 1 and the resources defined by the paging message 1130 for itsuplink transmission of message 3 (a transmission 1160). If not, then ifthe terminal device can detect the paging message 1140 at CE level 2, ituses the resources defined by that paging message for its uplink message3 1170 at CE level 2. If not, then assuming the terminal device candetect the paging message 1150 at CE level 3, it uses the resourcesdefined by that paging message 1150 to send its uplink message 3 1180 atCE level 3.

Therefore, in FIG. 11, different system resources are used to transmitrespective pairs of DCIs which schedule paging messages (DCIs 1100,1110, 1120) and different resources are used to provide the respectivepaging messages at the different respective CE levels (1130, 1140,1150). The terminal device responds to the lowest one of these CE levelpaging messages which it can successfully detect, and transmits anuplink message 1160, 1170 or 1180 using the resources defined by therespective paging message. Note that in embodiments, the terminal devicesends only one of the uplink message 3s (1160, 1170, 1180), being theone instance of message 3 at the CE level defined by the lowest CE levelpaging message successfully decoded by the terminal device. Thisprovides an example of the controller of the terminal device beingconfigured to set a CE mode according to the CE mode of a detectedpaging signal.

In further examples, the paging message and/or the DCI which schedulesthe paging message are not in fact differentiated by CE level. That isto say, in these further examples, a single paging message and/or asingle DCI which schedules the paging message is used. In such examples,the LC-MTC terminal device can transmit the first message 3 transmissionat the highest CE level (corresponding to the greatest number ofrepetitions) the base station can then adjust the CE level (ifappropriate) using information provided with the HARQ DCI. In this way,a second HARQ re-transmission can be transmitted at a different (lower)repetition level corresponding to a different (lower) CE level specifiedas part of the HARQ response. This provides an example of a terminaldevice configured to perform wireless communication with the basestation using the allocated communications resource by sending theconnection request message using a predetermined CE mode, and to receiveinformation from the base station, in response to that connectionrequest message, indicating a required CE mode.

In further examples, the paging message and/or the DCI which schedulesthe paging message are not differentiated by CE level. However, theterminal device can perform early termination of its message 3repetition based on its own CE level. So, for example, the arrangementshown schematically in FIG. 12 may be used, in which a single DCI 1200schedules a single paging message 1210 at CE level 3. The paging messagedefines resources for use by the terminal device in transmitting itsmessage 3 1220. The resources define sufficient time (from t₄ through tot₇) to allow the terminal device to transmit the message 3 1220 at CElevel 3, the highest level of repetition in this example. However, theterminal device is aware of its own CE level and is therefore aware thatthere is no need to transmit message 3 at a higher repetition level thanthe repetition level defined by the terminal device's own CE level.Therefore, if the CE level of the terminal device lower than level 3,the terminal device can terminate transmission of message 3 early, whichis to say, at a lower number of repetitions than those available usingthe scheduled resources provided by the paging message 1210. Thisprovides an example of a terminal device configured to receive thepaging signal using a predetermined CE mode and to perform wirelesscommunication using a CE mode associated with the terminal device.

In the specific example of FIG. 12, if the terminal device has a CElevel of 1, the message 3 transmission can be terminated after a numberof repetitions corresponding to CE level 1, at a time t₅. If theterminal device has a CE level of 2, the transmission of the message 3can be terminated by the terminal device at a time t₆ corresponding to anumber of repetitions at least equal to those applicable to CE level 2.The time points at which termination takes place (t₅ and t₆) can bepredefined by the network or by specification known to both the basestation and the terminal device. Assuming that the early terminationpoints t₅ and t₆ are defined, the base station is aware of thetermination points and is able to send its HARQ response at theappropriate time conforming to the normal HARQ timing constraints. Asdiscussed above, the DCI of the HARQ can provide information to theterminal device amending the CE level to be used by the base station,potentially to match that of the terminal device.

In example embodiments, the DCI which schedules the paging message,and/or the paging message itself, can indicate whether or not a reducedRACH process (where the PRACH and/or the RAR are omitted) is to be used.This information can be provided explicitly as a flag or data field, orcan be provided implicitly, in that the absence of message 3 grantinformation in the paging message can indicate that a full RACH processshould be used. This arrangement can provide improved flexibility forthe scheduling algorithms used at the base station. The detection of apresence or absence of the grant information in the paging messageprovides an example of detecting whether the paging signal comprisesinformation defining an allocation of a communications resource for useby the terminal device to send a connection request message to the basestation. In response to a detection that the paging signal does notcomprise information defining the allocation of the communicationsresource, the controller of the terminal device can control thetransceiver to perform a radio channel allocation (RACH) procedure withthe base station in order for the terminal device to be allocated thecommunications resource.

In other example embodiments, if the base station indicates that thefull RACH process (including PRACH and RAR) should be used, the basestation can additionally indicate in the paging message and/or in theDCI scheduling the paging message, the RACH resource to be used for thePRACH preamble. That is to say, the base station can reserve an RACHresource for that particular terminal device to use for its PRACHpreamble, which can reduce its use of collision.

In example embodiments, if the reduced RACH process were to fail, thatis to say, the message 3 (as the first uplink transmission) were to failto reach the base station or to be successfully detected and decoded bythe base station, the terminal device could re-try by performing thefull RACH process, for example at the same CE level as that used for thefailed message 3. As before, if the RACH process were not successful atthat CE level, the CE level could be ramped up. This provides an exampleof a terminal device in which, when the controller detects that the basestation has not acknowledged a connection request message sent inresponse to a paging signal directed to that terminal device, thecontroller is configured to follow a radio channel allocation procedurewith the base station. For example, the controller may be configured tofollow a radio channel allocation procedure using the CE mode at whichthe connection message was sent.

Similarly, if the terminal device fails even to detect the presence ofthe uplink allocation in the paging message, it will revert to the fullRACH procedure. This is an example of a base station in which, for aterminal device from which the base station does not receive aconnection request message in response to a paging signal directed tothat terminal device, the controller (of the base station) is configuredto follow a radio channel allocation procedure with that terminaldevice.

The operations of the terminal device and the base station as describedmay be carried out by the respective controller interacting with thetransmitter and receiver (which collectively provide a respectivetransceiver). The functions may be performed (in examples) at least inpart by computer software, such as computer software stored on anon-transitory machine-readable storage medium (such as a magnetic oroptical disk) being run by (or used to control operations of) acomputer.

FIG. 13 is a schematic flowchart summarizing a method of operation ofterminal device for use in a wireless telecommunications system andconfigured to perform wireless communication with a base station; themethod comprising:

detecting (at a step 1300) a wireless paging signal from the basestation;

detecting (at a step 1310) whether the paging signal comprisesinformation defining an allocation of a communications resource for useby the terminal device to send a connection request message to the basestation;

controlling (at a step 1320) the transceiver, in response to a detectionthat the paging signal does not comprise information defining theallocation of the communications resource, to perform a radio channelallocation procedure with the base station in order for the terminaldevice to be allocated the communications resource; and

controlling (at a step 1330) the transceiver to establish wirelesscommunication with the base station by sending the connection requestmessage using the allocated communications resource.

FIG. 14 is a schematic diagram summarizing a method of operation of abase station for use in a wireless telecommunications system andconfigured to perform wireless communication with a terminal device; themethod comprising:

sending (at a step 1400) a wireless paging signal to the terminaldevice, the paging signal comprising information defining an allocationof a communications resource for use by the terminal device to send aconnection request message to the base station; and

establishing (at a step 1410) wireless communication with the terminaldevice by receiving the connection request message using the allocatedcommunications resource.

Where methods of processing, coding or decoding are discussed above, itwill be appreciated that apparatus configured to perform such methodsare also considered to represent embodiments of the disclosure.

In so far as embodiments of the disclosure have been described as beingimplemented, at least in part, by software-controlled data processingapparatus, it will be appreciated that a non-transitory machine-readablemedium carrying such software, such as an optical disk, a magnetic disk,semiconductor memory or the like, is also considered to represent anembodiment of the present disclosure.

It will be apparent that numerous modifications and variations of thepresent disclosure are possible in light of the above teachings. It istherefore to be understood that within the scope of the appended claims,the technology may be practiced otherwise than as specifically describedherein.

Respective aspects and features of embodiments of the disclosure aredefined by the following numbered clauses:

1. A terminal device for use in a wireless telecommunications system,the terminal device comprising:

a transceiver configured to perform wireless communication with a basestation; and

a controller configured to:

control the transceiver to detect a wireless paging signal from the basestation;

detect whether the paging signal comprises information defining anallocation of a communications resource for use by the terminal deviceto send a connection request message to the base station;

control the transceiver, in response to a detection that the pagingsignal does not comprise information defining the allocation of thecommunications resource, to perform a radio channel allocation procedurewith the base station in order for the terminal device to be allocatedthe communications resource; and

control the transceiver to establish wireless communication with thebase station by sending the connection request message using theallocated communications resource.

2. A terminal device according to clause 1, in which the communicationsresource comprises one or more of: one or more radio frequency bands; atemporary radio network identifier and one or more transmission timeslots.

3. A terminal device according to clause 1 or clause 2, in which thepaging signal comprises a data field defining the communicationsresource.

4. A terminal device according to any one of clauses 1 to 3, in whichthe paging signal comprises a first portion and a second portion, thefirst portion comprising scheduling data scheduling the transmission ofthe second portion, the first portion comprising a data field definingthe communications resource.5. A terminal device according to any one of clauses 1 to 3, in whichthe paging signal comprises a first portion and a second portion, thefirst portion comprising scheduling data scheduling the transmission ofthe second portion, the second portion comprising a data field definingthe communications resource.6. A terminal device according to any one of the preceding clauses, theterminal device being configured to selectively operate at multiplecoverage enhancement (CE) modes, each CE mode corresponding to adifferent respective number of repetitions of wireless data signals toor from the terminal device.7. A terminal device according to clause 6, in which the controller isconfigured to set a CE mode according to the CE mode of a detectedpaging signal.8. A terminal device according to clause 6, configured to performwireless communication with the base station using the allocatedcommunications resource by sending the connection request message usinga predetermined CE mode, and to receive information from the basestation, in response to that connection request message, indicating arequired CE mode.9. A terminal device according to clause 6, configured to receive thepaging signal using a predetermined CE mode and to perform wirelesscommunication using a CE mode associated with the terminal device.10. A terminal device according to clause 9, in which, when thecontroller detects that the base station has not acknowledged aconnection request message sent in response to a paging signal directedto that terminal device, the controller is configured to follow a radiochannel allocation procedure with the base station.11. A terminal device according to clause 10, in which the controller isconfigured to follow a radio channel allocation procedure using the CEmode at which the connection message was sent.12. A base station for use in a wireless telecommunications system, thebase station comprising:

a transceiver configured to perform wireless communication with aterminal device; and

a controller configured to:

control the transceiver to send a wireless paging signal to the terminaldevice, the paging signal comprising information defining an allocationof a communications resource for use by the terminal device to send aconnection request message to the base station; and

control the transceiver to establish wireless communication with theterminal device by receiving the connection request message using theallocated communications resource.

13. A base station according to clause 12, in which the communicationsresource comprises one or more of: one or more radio frequency bands; atemporary radio network identifier and one or more transmission timeslots.

14. A base station according to clause 12 or clause 13, in which thepaging signal comprises a data field defining the communicationsresource.

15. A base station according to any one of clauses 12 to 14, in whichthe paging signal comprises a first portion and a second portion, thefirst portion comprising scheduling data scheduling the transmission ofthe second portion, the first portion comprising a data field definingthe communications resource.16. A base station according to any one of clauses 12 to 14, in whichthe paging signal comprises a first portion and a second portion, thefirst portion comprising scheduling data scheduling the transmission ofthe second portion, the second portion comprising a data field definingthe communications resource.17. A base station according to any one of clauses 12 to 15, the basestation being configured to selectively operate at multiple coverageenhancement (CE) modes for communication with the terminal device, eachCE mode corresponding to a different respective number of repetitions ofwireless data signals to or from the terminal device.18. A base station according to clause 17, configured to receive theconnection request message using a predetermined CE mode, and to sendinformation to the terminal device which sent that connection requestmessage, indicating a required CE mode.19. A base station according to clause 17, in which the controller isconfigured to control the transceiver to send multiple paging signals atdifferent respective CE modes, each paging signal defining a respectivecommunications resource for use by the terminal device.20. A base station according to clause 13, in which the communicationsresource comprises at least a transmission time slot defining a subframeamongst plural consecutive subframes, the controller being configured tocontrol the transceiver to receive the connection request message in thedefined subframe and at least one temporally following subframe.21. A base station according to clause 20, in which:

the base station is configured to selectively operate at multiplecoverage enhancement (CE) modes for communication with the terminaldevice, each CE mode corresponding to a different respective number ofrepetitions of wireless data signals to or from the terminal device; and

the controller is configured to control the transceiver to receive theconnection request message in the defined subframe and a number oftemporally following subframes dependent upon the number of repetitionsused in the CE mode applicable to communications from the terminaldevice.

22. A base station according to clause 21, in which the number oftemporally following subframes is equal to the number of repetitions.

23. A base station according to claim 12, in which, for a terminaldevice from which the base station does not receive a connection requestmessage in response to a paging signal directed to that terminal device,the controller is configured to follow a radio channel allocationprocedure with that terminal device.24. A wireless telecommunications system comprising a terminal deviceaccording to any one of clauses 1 to 11 and a base station according toany one of clauses 12 to 22.25. A method of operation of a terminal device for use in a wirelesstelecommunications system and configured to perform wirelesscommunication with a base station; the method comprising:

detecting a wireless paging signal from the base station;

detecting whether the paging signal comprises information defining anallocation of a communications resource for use by the terminal deviceto send a connection request message to the base station;

controlling the transceiver, in response to a detection that the pagingsignal does not comprise information defining the allocation of thecommunications resource, to perform a radio channel allocation procedurewith the base station in order for the terminal device to be allocatedthe communications resource; and

controlling the transceiver to establish wireless communication with thebase station by sending the connection request message using theallocated communications resource.

26. Computer software which, when executed by a computer, causes thecomputer to perform the method of clause 25.

27. A storage medium which stores computer software according to clause26.

28. A method of operation base station for use in a wirelesstelecommunications system and configured to perform wirelesscommunication with a terminal device; the method comprising:

sending a wireless paging signal to the terminal device, the pagingsignal comprising information defining an allocation of a communicationsresource for use by the terminal device to send a connection requestmessage to the base station; and

establishing wireless communication with the terminal device byreceiving the connection request message using the allocatedcommunications resource.

29. Computer software which, when executed by a computer, causes thecomputer to perform the method of clause 28.

30. A storage medium which stores computer software according to clause29.

The invention claimed is:
 1. A terminal device for use in a wirelesstelecommunications system, the terminal device comprising: a transceiverconfigured to perform wireless communication with a base station; and acontroller configured to: control the transceiver to detect a wirelesspaging signal from the base station; detect whether the paging signalcomprises information defining an allocation of a communicationsresource for use by the terminal device to send a connection requestmessage to the base station; control the transceiver, in response to adetection that the paging signal does not comprise information definingthe allocation of the communications resource, to perform a radiochannel allocation procedure with the base station in order for theterminal device to be allocated the communications resource; and controlthe transceiver, in response to a detection that the paging signalcomprises information defining the allocation of the communicationsresource, to establish wireless communication with the base station bysending the connection request message using the allocatedcommunications resource, wherein the paging signal comprises a firstportion transmitted in a physical downlink control channel (PDCCH) and asecond portion transmitted in a physical downlink shared channel(PDSCH), the first portion comprising scheduling data scheduling thetransmission of the second portion and a data field defining thecommunications resource.
 2. The terminal device according to claim 1,wherein the communications resource comprises one or more of: one ormore radio frequency bands; a temporary radio network identifier and oneor more transmission time slots.
 3. The terminal device according toclaim 1, wherein the paging signal comprises a data field defining thecommunications resource.
 4. The terminal device according to claim 1,wherein the terminal device is configured to selectively operate atmultiple coverage enhancement (CE) modes, each CE mode corresponding toa different respective number of repetitions of wireless data signals toor from the terminal device.
 5. The terminal device according to claim4, wherein the controller is configured to set a CE mode according tothe CE mode of a detected paging signal.
 6. The terminal deviceaccording to claim 4, wherein the controller is configured to performwireless communication with the base station using the allocatedcommunications resource by sending the connection request message usinga predetermined CE mode; and receive information from the base station,in response to the connection request message, indicating a required CEmode.
 7. The terminal device according to claim 4, wherein thecontroller is configured to receive the paging signal using apredetermined CE mode; and perform wireless communication using a CEmode associated with the terminal device.
 8. A terminal device for usein a wireless telecommunications system, the terminal device comprising:a transceiver configured to perform wireless communication with a basestation; and a controller configured to control the transceiver todetect a wireless paging signal from the base station; detect whetherthe paging signal comprises information defining an allocation of acommunications resource for use by the terminal device to send aconnection request message to the base station; control the transceiver,in response to a detection that the paging signal does not compriseinformation defining the allocation of the communications resource, toperform a radio channel allocation procedure with the base station inorder for the terminal device to be allocated the communicationsresource; and control the transceiver to establish wirelesscommunication with the base station by sending the connection requestmessage using the allocated communications resource, wherein theterminal device is configured to selectively operate at multiplecoverage enhancement (CE) modes, each CE mode corresponding to adifferent respective number of repetitions of wireless data signals toor from the terminal device, and the controller is configured to receivethe paging signal using a predetermined CE mode; perform wirelesscommunication using a CE mode associated with the terminal device; andwhen the controller detects that the base station has not acknowledged aconnection request message sent in response to a paging signal directedto that terminal device, the controller is configured to follow a radiochannel allocation procedure with the base station.
 9. The terminaldevice according to claim 8, wherein the controller is configured tofollow a radio channel allocation procedure using the CE mode at whichthe connection request message was sent.
 10. A base station for use in awireless telecommunications system, the base station comprising: atransceiver configured to perform wireless communication with a terminaldevice; and a controller configured to: control the transceiver to senda wireless paging signal to the terminal device, the paging signalcomprising information defining an allocation of a communicationsresource for use by the terminal device to send a connection requestmessage to the base station; and control the transceiver to establishwireless communication with the terminal device by receiving theconnection request message using the allocated communications resource,wherein the base station is configured to selectively operate atmultiple coverage enhancement (CE) modes for communication with theterminal device, each CE mode corresponding to a different respectivenumber of repetitions of wireless data signals to or from the terminaldevice, and the controller is configured to control the transceiver tosend multiple paging signals at different respective CE modes, eachpaging signal defining a respective communications resource for use bythe terminal device.
 11. The base station according to claim 10, whereinthe communications resource comprises one or more of: one or more radiofrequency bands; a temporary radio network identifier and one or moretransmission time slots.
 12. The base station according to claim 10,wherein the paging signal comprises a data field defining thecommunications resource.
 13. The base station according to claim 10,wherein the paging signal comprises a first portion and a secondportion, the first portion comprising scheduling data scheduling thetransmission of the second portion, the first portion comprising a datafield defining the communications resource.
 14. The base stationaccording to claim 10, wherein the paging signal comprises a firstportion and a second portion, the first portion comprising schedulingdata scheduling the transmission of the second portion, the secondportion comprising a data field defining the communications resource.15. The base station according to claim 10, wherein the controller isconfigured to: receive the connection request message using apredetermined CE mode; and send information to the terminal device whichsent that connection request message, indicating a required CE mode. 16.A method of operation of a terminal device for use in a wirelesstelecommunications system and configured to perform wirelesscommunication with a base station; the method comprising: detecting awireless paging signal from the base station; detecting whether thepaging signal comprises information defining an allocation of acommunications resource for use by the terminal device to send aconnection request message to the base station; controlling thetransceiver, in response to a detection that the paging signal does notcomprise information defining the allocation of the communicationsresource, to perform a radio channel allocation procedure with the basestation in order for the terminal device to be allocated thecommunications resource; and controlling the transceiver, in response toa detection that the paging signal comprises information defining theallocation of the communications resource, to establish wirelesscommunication with the base station by sending the connection requestmessage using the allocated communications resource, wherein the pagingsignal comprises a first portion transmitted in a physical downlinkcontrol channel (PDCCH) and a second portion transmitted in a physicaldownlink shared channel (PDSCH), the first portion comprising schedulingdata scheduling the transmission of the second portion and a data fielddefining the communications resource.